I'm looking for a yaoi manga about a loner who is attached to his dog. When the dog passes away, he stops going to college, but then a human who claims to be his dog appears one day. The guy isn't his dog, but is his neighbor and gets into an accident or something in the end, and the main character (the loner) finds him in the hospital.

Thanks in advance if anyone can help me!

I found it. It's called Lovely Play: https://www.mangaupdates.com/series.html?id=143911

Surprisingly (or maybe not), there's another manga with the same plot called Tonari ni Kimi no Nukumori wo: https://www.mangaupdates.com/series.html?id=15063